The present invention relates generally to a user input and display device for controlling a range or the like and, more particularly, to such a device which is easily understandable by the user.
In a user operable control for an appliance, for example, a range surface unit heat control or a microwave oven power level control, it is highly desirable that each operation of the control result in an immediate indication to the user in an easily understood manner that the desired control function has in fact been selected. Additionally, the user should at any time be able to ascertain at a glance the state of the controls, i.e., the last control operation. Of course, the control must also send a signal to the rest of the apparatus or appliance to cause the selected function to actually occur.
Conventional mechanical switches, for example push button switches or rotary switches, although suffering certain limitations due to their mechanical nature, do serve well the function of indicating to the user just what has been selected. For example, in a range surface unit heat control comprising a row of pushbuttons arranged from low to high heat settings, the user pushes any one of the pushbuttons to select a desired heat setting. Additionally, by observing which of the pushbuttons is down, the user has immediate visual feedback as to the selection. Some controls of this general pushbutton type have included indicating lamps disposed beneath transparent pushbuttons and connected such that the pushbutton which is depressed lights up. Another type of mechanical switch conventionally used for such controls is simply a rotary switch having specific marked heat-setting positions.
With the recent development of so-called "electronic" appliances, particularly consumer microwave ovens but also conventional ranges, touch control and electronic display techniques have been adapted for use therein. One reason for this is the convenient interface of these electronic type inputs and display outputs with other electronic circuitry required in the appliance. Furthermore, such techniques make it possible to have a smooth control panel surface for good appearance and easy cleaning and eliminating reliability problems caused by mechanically movable switch contacts. Mechanically movable switch contacts, while generally capable of many years of trouble-free service, do eventually wear out simply because they employ moving parts. So-called touch switches do not employ moving parts but sense merely the presence of a human touch by sensing, for example, either a resistive bridging effect or a capacitive effect associated with a human touch.
The present invention advantageously combines touch switch user-input technology and bar graph display output technology to provide a simple and readily-understandable input/output device. The device permits the construction of an unintimidating control panel which a person may use with confidence. Further, it is fully compatible with digital logic control systems.